Such a safety device is know from FR-A 2 210 271. A mechanical cupboard is described therein, in which a plurality of cassette-like stored goods carriers can be slid in and out in two side racks. In between these two right and left stacked columns a feed platform can be driven in the height direction, so that individual stored goods carriers can be removed from the racks and be fed to an opening for taking out of stock (un-stocking). The withdrawal of the individual cassette-like stored goods carriers is effected by a magnet, which can be coupled to the front side of the stored goods carrier. Since however this withdrawing magnet has a certain structural length, by which the lateral width extent of the feed platform has to be extended, compact chain drives are finding increasing use for such devices for stocking and un-stocking load carriers in a rack or from a rack, as are described in DE 4 233 690 or DE 3 830 218 for example. Two chains parallel to one another are provided as drive lines, which run round diverting rollers and engage each selected stored goods carriers at the sides by means of pin-formed entraining elements.
In the first-mentioned state of the art the stocking/un-stocking opening is protected by a plurality of light barriers, in order to prevent intervention in the space of movement of the feed platform movable in height or on intervention to stop the drive straight away, in order to avoid injury to the operator. In the region of the circulating cupboard (paternoster cupboard) contact or switch rails are also known at the upper and/or lower edge of the stocking/un-stocking opening, which immediately stop the drive on forceful contact therewith.
Although both kinds of protective device have basically proved themselves as safety devices, it is disadvantage, particularly with the light barriers, that many operators do not wait for the feed platform to stop when store goods are arriving, but reach into the stocking/un-stocking opening, so that far too many "emergency stops" occur. This applies also to a removal or stocking table preceding the mechanical cupboard.